The objective of this contract is to maintain the Branch's capacity to test the efficacy of new anti-viral therapies in non-human primate animal models; these contracts represent a recompetition of the non- human primate models with the expansion to include in vitro testing, limited capacity to test combinations of therapies, and to obtain samples for pharmacokinetics studies. A companion contract will provide the capacity to obtain information on the pharmacokinetics of therapies in uninfected non-human primates and to analyze samples, gathered under these contracts, for drug levels. The SIV-infected macaque model is an important component of the animal model program within the Developmental Therapeutics Branch. Currently, there are contracts to provide anti-HIV testing in small animal models, including the SCID-hu mouse infected with HIV, FeLV or FIV infection of cats, and Rauscher and LP-BM-5 infection of mice. The SIV-macaque system provides a model of disease that is very similar to HIV infection in humans. As such, it provides the opportunity to study the effects of potential new therapies on disease progression using surrogate markers similar to those used in human clinical trials.